Multisite

MediaThèque (or MediaBrary) has its own way to adapt to the multisite configuration of WordPress. As you may know, the native WordPress Media Library is not shared across the network of sites. Each site has its own Media Library. MediaThèque first care about users, not sites. As a result the personal MediaBrary of a user is shared across all sites the user is a member of.

Activation

MediaThèque can only network widely activated. So you'll need to activate the plugin form the Plugins Network Administration.

MediaThèque management

The super administrator can manage all personal MediaBraries within the Network Administration. To access it, he simply needs to go on the User MediaBrary Network Administration screen.